Organic electroluminescent materials and devices

ABSTRACT

Novel heteroleptic iridium complexes are disclosed. The complexes contain a phenyl pyridine ligand and another ligand containing a dibenzofuran, dibenzothiophene, dibenzoselenophene, or carbazole linked to an imidazole or benzimidazole fragment. These complexes are useful materials when incorporated into OLED devices.

The claimed invention was made by, on behalf of, and/or in connection with one or more of the following parties to a joint university corporation research agreement: Regents of the University of Michigan, Princeton University, The University of Southern California, and the Universal Display Corporation. The agreement was in effect on and before the date the claimed invention was made, and the claimed invention was made as a result of activities undertaken within the scope of the agreement.

FIELD OF THE INVENTION

The present invention relates to novel heteroleptic iridium complexes, particularly complexes containing a dibenzofuran, dibenzothiophene, dibenzoselenophene, or carbazole fragment linked to an imidazole or benzimidazole. The complexes are useful as emitters in OLED devices.

BACKGROUND

Opto-electronic devices that make use of organic materials are becoming increasingly desirable for a number of reasons. Many of the materials used to make such devices are relatively inexpensive, so organic opto-electronic devices have the potential for cost advantages over inorganic devices. In addition, the inherent properties of organic materials, such as their flexibility, may make them well suited for particular applications such as fabrication on a flexible substrate. Examples of organic opto-electronic devices include organic light emitting devices (OLEDs), organic phototransistors, organic photovoltaic cells, and organic photodetectors. For OLEDs, the organic materials may have performance advantages over conventional materials. For example, the wavelength at which an organic emissive layer emits light may generally be readily tuned with appropriate dopants.

OLEDs make use of thin organic films that emit light when voltage is applied across the device. OLEDs are becoming an increasingly interesting technology for use in applications such as flat panel displays, illumination, and backlighting. Several OLED materials and configurations are described in U.S. Pat. Nos. 5,844,363, 6,303,238, and 5,707,745, which are incorporated herein by reference in their entirety.

One application for phosphorescent emissive molecules is a full color display. Industry standards for such a display call for pixels adapted to emit particular colors, referred to as “saturated” colors. In particular, these standards call for saturated red, green, and blue pixels. Color may be measured using CIE coordinates, which are well known to the art.

One example of a green emissive molecule is tris(2-phenylpyridine) iridium, denoted Ir(ppy)₃, which has the following structure:

In this, and later figures herein, we depict the dative bond from nitrogen to metal (here, Ir) as a straight line.

As used herein, the term “organic” includes polymeric materials as well as small molecule organic materials that may be used to fabricate organic opto-electronic devices. “Small molecule” refers to any organic material that is not a polymer, and “small molecules” may actually be quite large. Small molecules may include repeat units in some circumstances. For example, using a long chain alkyl group as a substituent does not remove a molecule from the “small molecule” class. Small molecules may also be incorporated into polymers, for example as a pendent group on a polymer backbone or as a part of the backbone. Small molecules may also serve as the core moiety of a dendrimer, which consists of a series of chemical shells built on the core moiety. The core moiety of a dendrimer may be a fluorescent or phosphorescent small molecule emitter. A dendrimer may be a “small molecule,” and it is believed that all dendrimers currently used in the field of OLEDs are small molecules.

As used herein, “top” means furthest away from the substrate, while “bottom” means closest to the substrate. Where a first layer is described as “disposed over” a second layer, the first layer is disposed further away from substrate. There may be other layers between the first and second layer, unless it is specified that the first layer is “in contact with” the second layer. For example, a cathode may be described as “disposed over” an anode, even though there are various organic layers in between.

As used herein, “solution processible” means capable of being dissolved, dispersed, or transported in and/or deposited from a liquid medium, either in solution or suspension form.

A ligand may be referred to as “photoactive” when it is believed that the ligand directly contributes to the photoactive properties of an emissive material. A ligand may be referred to as “ancillary” when it is believed that the ligand does not contribute to the photoactive properties of an emissive material, although an ancillary ligand may alter the properties of a photoactive ligand.

As used herein, and as would be generally understood by one skilled in the art, a first “Highest Occupied Molecular Orbital” (HOMO) or “Lowest Unoccupied Molecular Orbital” (LUMO) energy level is “greater than” or “higher than” a second HOMO or LUMO energy level if the first energy level is closer to the vacuum energy level. Since ionization potentials (IP) are measured as a negative energy relative to a vacuum level, a higher HOMO energy level corresponds to an IP having a smaller absolute value (an IP that is less negative). Similarly, a higher LUMO energy level corresponds to an electron affinity (EA) having a smaller absolute value (an EA that is less negative). On a conventional energy level diagram, with the vacuum level at the top, the LUMO energy level of a material is higher than the HOMO energy level of the same material. A “higher” HOMO or LUMO energy level appears closer to the top of such a diagram than a “lower” HOMO or LUMO energy level.

As used herein, and as would be generally understood by one skilled in the art, a first work function is “greater than” or “higher than” a second work function if the first work function has a higher absolute value. Because work functions are generally measured as negative numbers relative to vacuum level, this means that a “higher” work function is more negative. On a conventional energy level diagram, with the vacuum level at the top, a “higher” work function is illustrated as further away from the vacuum level in the downward direction. Thus, the definitions of HOMO and LUMO energy levels follow a different convention than work functions.

More details on OLEDs, and the definitions described above, can be found in U.S. Pat. No. 7,279,704, which is incorporated herein by reference in its entirety.

SUMMARY OF THE INVENTION

A compound having the formula:

is provided. In the compound of Formula I, R₁, R₂, and R₃ represent mono-, di-, tri-, tetra-substitution or no substitution. R, R′, R₁, R₂, R₃, R₄, R₅, and R₆ are independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof. Any adjacent R, R′, R₁, R₂, R₃, R₄, R₅, and R₆ are optionally linked, X is selected from the group consisting of BR, NR, PR, O, S, Se, C═O, S═O, SO₂, CRR′, SiRR′, and GeRR′, and wherein m is 1 or 2.

In one aspect, X is selected from the group consisting of S, O, Se, and NR″; and wherein R″ is selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, neopentyl, cyclopentyl, cyclohexyl, phenyl, 2,6-dimethylphenyl, and 2,6-diiosopropylphenyl.

In one aspect, the compound has the formula:

In one aspect, the compound has the formula:

R₇ represents mono-, di-, tri-, tetra-substitution or no substitution, and wherein R₇ is selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.

In one aspect, the compound has the formula:

In one aspect, the compound has the formula:

In one aspect, m is 2. In one aspect, X is O. In one aspect, R₄ is alkyl. In one aspect, R₄ is aryl or substituted aryl.

In one aspect, R₄ is

R′₁, R′₂, and R′₃ are independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof. R′₃ represents mono-, di-, tri-, tetra-substitution or no substitution, and at least one of R′₁ and R′₂ is not hydrogen or deuterium. Ring C is 5-membered or 6-membered carbocyclic or heterocyclic ring, and any adjacent R′₁, R′₂, and R′₃ may be optionally joined to form a ring.

In one aspect, both R′₁ and R′₂ are not hydrogen or deuterium. In another aspect, R′₁, R′₂, and R′₃ are independently selected from the group consisting of hydrogen, deuterium, methyl, ethyl, isopropyl, isobutyl, neopentyl, cyclopentyl, cyclohexyl, phenyl, and combinations thereof.

In one aspect, R₁ and R₂ are independently selected from the group consisting of hydrogen, deuterium, alkyl, cycloalkyl, and combinations thereof.

In one aspect, the compound is selected from the group consisting of Compound 1-X to Compound 30-X.

In one aspect, a first device is provided. The first device comprises a first organic light emitting device, further comprising an anode, a cathode, and an organic layer, disposed between the anode and the cathode, comprising a compound having the formula:

is provided. In the compound of Formula I, R₁, R₂, and R₃ represent mono-, di-, tri-, tetra-substitution or no substitution. R, R′, R₁, R₂, R₃, R₄, R₅, and R₆ are independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof. Any adjacent R, R′, R₁, R₂, R₃, R₄, R₅, and R₆ are optionally linked, X is selected from the group consisting of BR, NR, PR, O, S, Se, C═O, S═O, SO₂, CRR′, SiRR′, and GeRR′, and wherein m is 1 or 2.

In one aspect, the first device is a consumer product. In one aspect, the first device is an organic light-emitting device. In one aspect, the first device comprises a lighting panel. In one aspect, the organic layer is an emissive layer and the compound is an emissive dopant. In another aspect, the organic layer is an emissive layer and the compound is a non-emissive dopant.

In one aspect, the organic layer further comprises a host. In one aspect, the host comprises a triphenylene containing benzo-fused thiophene or benzo-fused furan, wherein any substituent in the host is an unfused substituent independently selected from the group consisting of C_(n)H_(2n+1), OC_(n)H_(2n+1), OAr₁, N(C_(n)H_(2n+1))₂, N(Ar₁)(Ar₂), CH═CH—C_(n)H_(2n+1), C≡CHC_(n)H_(2n+1), Ar₁, Ar₁—Ar₂, C_(n)H_(2n)—Ar₁, or no substitution, wherein n is from 1 to 10, and wherein Ar₁ and Ar₂ are independently selected from the group consisting of benzene, biphenyl, naphthalene, triphenylene, carbazole, and heteroaromatic analogs thereof.

In one aspect, the host comprises one or more compounds having the formula:

wherein p is 0 or 1.

In one aspect, the host is selected from the group consisting of:

and combinations thereof. In one aspect, the host comprises a metal complex.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an organic light emitting device.

FIG. 2 shows an inverted organic light emitting device that does not have a separate electron transport layer.

FIG. 3 shows a compound of Formula I.

DETAILED DESCRIPTION

Generally, an OLED comprises at least one organic layer disposed between and electrically connected to an anode and a cathode. When a current is applied, the anode injects holes and the cathode injects electrons into the organic layer(s). The injected holes and electrons each migrate toward the oppositely charged electrode. When an electron and hole localize on the same molecule, an “exciton,” which is a localized electron-hole pair having an excited energy state, is formed. Light is emitted when the exciton relaxes via a photoemissive mechanism. In some cases, the exciton may be localized on an excimer or an exciplex. Non-radiative mechanisms, such as thermal relaxation, may also occur, but are generally considered undesirable.

The initial OLEDs used emissive molecules that emitted light from their singlet states (“fluorescence”) as disclosed, for example, in U.S. Pat. No. 4,769,292, which is incorporated by reference in its entirety. Fluorescent emission generally occurs in a time frame of less than 10 nanoseconds.

More recently, OLEDs having emissive materials that emit light from triplet states (“phosphorescence”) have been demonstrated. Baldo et al., “Highly Efficient Phosphorescent Emission from Organic Electroluminescent Devices,” Nature, vol. 395, 151-154, 1998; (“Baldo-I”) and Baldo et al., “Very high-efficiency green organic light-emitting devices based on electrophosphorescence,” Appl. Phys. Lett., vol. 75, No. 3, 4-6 (1999) (“Baldo-II”), which are incorporated by reference in their entireties. Phosphorescence is described in more detail in U.S. Pat. No. 7,279,704 at cols. 5-6, which are incorporated by reference.

FIG. 1 shows an organic light emitting device 100. The figures are not necessarily drawn to scale. Device 100 may include a substrate 110, an anode 115, a hole injection layer 120, a hole transport layer 125, an electron blocking layer 130, an emissive layer 135, a hole blocking layer 140, an electron transport layer 145, an electron injection layer 150, a protective layer 155, and a cathode 160. Cathode 160 is a compound cathode having a first conductive layer 162 and a second conductive layer 164. Device 100 may be fabricated by depositing the layers described, in order. The properties and functions of these various layers, as well as example materials, are described in more detail in U.S. Pat. No. 7,279,704 at cols. 6-10, which are incorporated by reference.

More examples for each of these layers are available. For example, a flexible and transparent substrate-anode combination is disclosed in U.S. Pat. No. 5,844,363, which is incorporated by reference in its entirety. An example of a p-doped hole transport layer is m-MTDATA doped with F.sub.4-TCNQ at a molar ratio of 50:1, as disclosed in U.S. Patent Application Publication No. 2003/0230980, which is incorporated by reference in its entirety. Examples of emissive and host materials are disclosed in U.S. Pat. No. 6,303,238 to Thompson et al., which is incorporated by reference in its entirety. An example of an n-doped electron transport layer is BPhen doped with Li at a molar ratio of 1:1, as disclosed in U.S. Patent Application Publication No. 2003/0230980, which is incorporated by reference in its entirety. U.S. Pat. Nos. 5,703,436 and 5,707,745, which are incorporated by reference in their entireties, disclose examples of cathodes including compound cathodes having a thin layer of metal such as Mg:Ag with an overlying transparent, electrically-conductive, sputter-deposited ITO layer. The theory and use of blocking layers is described in more detail in U.S. Pat. No. 6,097,147 and U.S. Patent Application Publication No. 2003/0230980, which are incorporated by reference in their entireties. Examples of injection layers are provided in U.S. Patent Application Publication No. 2004/0174116, which is incorporated by reference in its entirety. A description of protective layers may be found in U.S. Patent Application Publication No. 2004/0174116, which is incorporated by reference in its entirety.

FIG. 2 shows an inverted OLED 200. The device includes a substrate 210, a cathode 215, an emissive layer 220, a hole transport layer 225, and an anode 230. Device 200 may be fabricated by depositing the layers described, in order. Because the most common OLED configuration has a cathode disposed over the anode, and device 200 has cathode 215 disposed under anode 230, device 200 may be referred to as an “inverted” OLED. Materials similar to those described with respect to device 100 may be used in the corresponding layers of device 200. FIG. 2 provides one example of how some layers may be omitted from the structure of device 100.

The simple layered structure illustrated in FIGS. 1 and 2 is provided by way of non-limiting example, and it is understood that embodiments of the invention may be used in connection with a wide variety of other structures. The specific materials and structures described are exemplary in nature, and other materials and structures may be used. Functional OLEDs may be achieved by combining the various layers described in different ways, or layers may be omitted entirely, based on design, performance, and cost factors. Other layers not specifically described may also be included. Materials other than those specifically described may be used. Although many of the examples provided herein describe various layers as comprising a single material, it is understood that combinations of materials, such as a mixture of host and dopant, or more generally a mixture, may be used. Also, the layers may have various sublayers. The names given to the various layers herein are not intended to be strictly limiting. For example, in device 200, hole transport layer 225 transports holes and injects holes into emissive layer 220, and may be described as a hole transport layer or a hole injection layer. In one embodiment, an OLED may be described as having an “organic layer” disposed between a cathode and an anode. This organic layer may comprise a single layer, or may further comprise multiple layers of different organic materials as described, for example, with respect to FIGS. 1 and 2.

Structures and materials not specifically described may also be used, such as OLEDs comprised of polymeric materials (PLEDs) such as disclosed in U.S. Pat. No. 5,247,190 to Friend et al., which is incorporated by reference in its entirety. By way of further example, OLEDs having a single organic layer may be used. OLEDs may be stacked, for example as described in U.S. Pat. No. 5,707,745 to Forrest et al, which is incorporated by reference in its entirety. The OLED structure may deviate from the simple layered structure illustrated in FIGS. 1 and 2. For example, the substrate may include an angled reflective surface to improve out-coupling, such as a mesa structure as described in U.S. Pat. No. 6,091,195 to Forrest et al., and/or a pit structure as described in U.S. Pat. No. 5,834,893 to Bulovic et al., which are incorporated by reference in their entireties.

Unless otherwise specified, any of the layers of the various embodiments may be deposited by any suitable method. For the organic layers, preferred methods include thermal evaporation, ink-jet, such as described in U.S. Pat. Nos. 6,013,982 and 6,087,196, which are incorporated by reference in their entireties, organic vapor phase deposition (OVPD), such as described in U.S. Pat. No. 6,337,102 to Forrest et al., which is incorporated by reference in its entirety, and deposition by organic vapor jet printing (OVJP), such as described in U.S. patent application Ser. No. 10/233,470, which is incorporated by reference in its entirety. Other suitable deposition methods include spin coating and other solution based processes. Solution based processes are preferably carried out in nitrogen or an inert atmosphere. For the other layers, preferred methods include thermal evaporation. Preferred patterning methods include deposition through a mask, cold welding such as described in U.S. Pat. Nos. 6,294,398 and 6,468,819, which are incorporated by reference in their entireties, and patterning associated with some of the deposition methods such as ink-jet and OVJD. Other methods may also be used. The materials to be deposited may be modified to make them compatible with a particular deposition method. For example, substituents such as alkyl and aryl groups, branched or unbranched, and preferably containing at least 3 carbons, may be used in small molecules to enhance their ability to undergo solution processing. Substituents having 20 carbons or more may be used, and 3-20 carbons is a preferred range. Materials with asymmetric structures may have better solution processibility than those having symmetric structures, because asymmetric materials may have a lower tendency to recrystallize. Dendrimer substituents may be used to enhance the ability of small molecules to undergo solution processing.

Devices fabricated in accordance with embodiments of the invention may be incorporated into a wide variety of consumer products, including flat panel displays, computer monitors, medical monitors, televisions, billboards, lights for interior or exterior illumination and/or signaling, heads up displays, fully transparent displays, flexible displays, laser printers, telephones, cell phones, personal digital assistants (PDAs), laptop computers, digital cameras, camcorders, viewfinders, micro-displays, vehicles, a large area wall, theater or stadium screen, or a sign. Various control mechanisms may be used to control devices fabricated in accordance with the present invention, including passive matrix and active matrix. Many of the devices are intended for use in a temperature range comfortable to humans, such as 18 degrees C. to 30 degrees C., and more preferably at room temperature (20-25 degrees C.).

The materials and structures described herein may have applications in devices other than OLEDs. For example, other optoelectronic devices such as organic solar cells and organic photodetectors may employ the materials and structures. More generally, organic devices, such as organic transistors, may employ the materials and structures.

The terms halo, halogen, alkyl, cycloalkyl, alkenyl, alkynyl, arylkyl, heterocyclic group, aryl, aromatic group, and heteroaryl are known to the art, and are defined in U.S. Pat. No. 7,279,704 at cols. 31-32, which are incorporated herein by reference.

A compound having the formula:

is provided. In the compound of Formula I, R₁, R₂, and R₃ represent mono-, di-, tri-, tetra-substitution or no substitution. R, R′, R₁, R₂, R₃, R₄, R₅, and R₆ are independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof. Any adjacent R, R′, R₁, R₂, R₃, R₄, R₅, and R₆ are optionally linked, X is selected from the group consisting of BR, NR, PR, O, S, Se, C═O, S═O, SO₂, CRR′, SiRR′, and GeRR′, and wherein m is 1 or 2.

It has been unexpectedly discovered that combining ppy (2-phenylpyridine) and DBX-imidazole or DBX-benzimidazole ligands to form heteroleptic iridium complexes not known in literature results in compounds with superior properties. The term DBX refers to the structure shown below, where X can be any of the atoms or groups disclosed herein, and where the DBX ring may be further substituted as also disclosed herein.

Thus, for example, DBT is dibenzothiophene (X═S), and DBF is dibenzofuran (X═O). Compounds of Formula I, when incorporated into OLED devices can result in devices with improved efficiency and lifetimes. The compounds of Formula I can be tuned to emit a more saturated green color.

In one embodiment, X is selected from the group consisting of S, O, Se, and NR″; and wherein R″ is selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, neopentyl, cyclopentyl, cyclohexyl, phenyl, 2,6-dimethylphenyl, and 2,6-diiosopropylphenyl.

In one embodiment, the compound has the formula:

In one embodiment, the compound has the formula:

R₇ represents mono-, di-, tri-, tetra-substitution or no substitution, and wherein R₇ is selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.

In one embodiment, the compound has the formula:

In one embodiment, the compound has the formula:

In one embodiment, m is 2. In one embodiment, X is O. In one embodiment, R₄ is alkyl. In one embodiment, R₄ is aryl or substituted aryl.

In one embodiment, R₄ is

R′₁, R′₂, and R′₃ are independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof. R′₃ represents mono-, di-, tri-, tetra-substitution or no substitution, and at least one of R′₁ and R′₂ is not hydrogen or deuterium. Ring C is 5-membered or 6-membered carbocyclic or heterocyclic ring, and any adjacent R′₁, R′₂, and R′₃ may be optionally joined to form a ring.

In one embodiment, both R′₁ and R′₂ are not hydrogen or deuterium. In another aspect, R′₁, R′₂, and R′₃ are independently selected from the group consisting of hydrogen, deuterium, methyl, ethyl, isopropyl, isobutyl, neopentyl, cyclopentyl, cyclohexyl, phenyl, and combinations thereof.

In one embodiment, R₁ and R₂ are independently selected from the group consisting of hydrogen, deuterium, alkyl, cycloalkyl, and combinations thereof.

In one embodiment, the compound is selected from the group consisting of:

Compounds 1-X to 30-X represent compounds where X may represent atoms or groups as disclosed herein. When X is a specific atom, the name of that particular compound corresponds to the nature of the X atom. Thus, when X═O, Compound 1-X is called Compound 1-O, and when X═S, Compound 1-X is called Compound 1-S, etc. The same naming scheme can be used for any of the other compounds described above.

In one embodiment, a first device is provided. The first device comprises a first organic light emitting device, further comprising an anode, a cathode, and an organic layer, disposed between the anode and the cathode, comprising a compound having the formula:

is provided. In the compound of Formula I, R₁, R₂, and R₃ represent mono-, di-, tri-, tetra-substitution or no substitution. R, R′. R₁, R₂, R₃, R₄, R₅, and R₆ are independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof. Any adjacent R, R′, R₁, R₂, R₃, R₄, R₅, and R₆ are optionally linked, X is selected from the group consisting of BR, NR, PR, O, S, Se, C═O, S═O, SO₂, CRR′, SiRR′, and GeRR′, and wherein m is 1 or 2. In one embodiment, X is selected from the group consisting of BR, NR, PR, O, S, Se, C═O, S═O, SO₂, CRR′, SiRR′, and GeRR′.

In one embodiment, the first device is a consumer product. In one embodiment, the first device is an organic light-emitting device. In one embodiment, the first device comprises a lighting panel. In one embodiment, the organic layer is an emissive layer and the compound is an emissive dopant. In another embodiment, the organic layer is an emissive layer and the compound is a non-emissive dopant.

In one embodiment, the organic layer further comprises a host. In one embodiment, the host comprises a triphenylene containing benzo-fused thiophene or benzo-fused furan, wherein any substituent in the host is an unfused substituent independently selected from the group consisting of C_(n)H_(2n+1), OC_(n)H_(2n+1), OAr₁, N(C_(n)H_(2n+1))₂, N(Ar₁)(Ar₂), CH═CH—C_(n)H_(2n+1), C≡CHC_(n)H_(2n+1), Ar₁, Ar₁—Ar₂, C_(n)H_(2n)—Ar₁, or no substitution, wherein n is from 1 to 10, and wherein Ar₁ and Ar₂ are independently selected from the group consisting of benzene, biphenyl, naphthalene, triphenylene, carbazole, and heteroaromatic analogs thereof.

In one embodiment, the host comprises one or more compounds having the formula:

wherein p is 0 or 1.

In one embodiment, the host is selected from the group consisting of:

and combinations thereof. In one embodiment, the host comprises a metal complex.

Device Examples

All example devices were fabricated by high vacuum (<10⁻⁷ Torr) thermal evaporation. The anode electrode is 1200 Å of indium tin oxide (ITO). The cathode consisted of 10 Å of LiF followed by 1,000 Å of Al. All devices are encapsulated with a glass lid sealed with an epoxy resin in a nitrogen glove box (<1 ppm of H₂O and O₂) immediately after fabrication, and a moisture getter was incorporated inside the package.

The organic stack of the device examples consisted of sequentially, from the ITO surface, 100 Å of Compound B or C as the hole injection layer (HIL), 300 Å of 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPD) as the hole transporting layer (HTL), 300 Å of the invention compound doped in compound D as host with 7, 10, 13 wt % of a compound of Formula I as the emissive layer (EML), 50 A of the compound D as block layer (BL), 450 Å of Alq₃ (tris-8-hydroxyquinoline aluminum) as the ETL. Comparative Examples with compound A or E was fabricated similarly to the Device Examples except that the compound A or E is used as the emitter in the EML.

The device structure and data are summarized in Table 1 and Table 2 from those devices. As used herein, Compounds A, B, C, D and E have the following structures:

TABLE 1 Device Structures of Invention Compounds and Comparative Compound A and B Example HIL HTL EML (300 Å, doping %) BL ETL Comparative Compound C NPD 300 Å Compound D Compound A Compound D Alq 450 Å Example 1 100 Å  7% 50 Å Comparative Compound C NPD 300 Å Compound D Compound A Compound D Alq 450 Å Example 2 100 Å 10% 50 Å Comparative Compound C NPD 300 Å Compound D Compound A Compound D Alq 450 Å Example 3 100 Å 13% 50 Å Comparative Compound C NPD 300 Å Compound D Compound E Compound D Alq 450 Å Example 4 100 Å  7% 50 Å Comparative Compound C NPD 300 Å Compound D Compound E Compound D Alq 450 Å Example 5 100 Å 10% 50 Å Example 1 Compound B NPD 300 Å Compound D Compound 1 Compound D Alq 450 Å 100 Å  7% 50 Å Example 2 Compound B NPD 300 Å Compound D Compound 1 Compound D Alq 450 Å 100 Å 10% 50 Å

TABLE 2 VTE Device Data of Invention Compounds and Comparative Compounds λ_(max) FWHM Voltage LE EQE PE LT80% x y (nm) (nm) (V) (Cd/A) (%) (lm/W) (h) Comparative 0.359 0.611 530 66 6.5 59.4 15.9 28.8 169 Example 1 Compound A Comparative 0.363 0.609 530 66 6.1 57.3 15.4 29.4 177 Example 2 Compound A Comparative 0.364 0.608 530 66 6.1 52.6 14.1 27.0 168 Example 3 Compound A Comparative 0.320 0.622 519 71 6.1 50.4 14 26.1 200 Example 4 Compound E Comparative 0.325 0.620 519 72 5.7 50.5 14 27.6 270 Example 5 Compound E Example 1 0.372 0.601 528 68 6.2 62.4 17.1 31.4 219.3 Compound 1-O Example 2 0.372 0.602 528 66 5.5 70.7 19.3 40.6 248.0 Compound 1-O

Table 2 is a summary of the device data. The luminous efficiency (LE), external quantum efficiency (EQE) and power efficiency (PE) were measured at 1000 nits, while the lifetime (LT_(80%)) was defined as the time required for the device to decay to 80% of its initial luminance under a constant current density of 40 mA/cm².

From Table 2 it can be seen that the external quantum efficiency EQE (19.3%), luminous efficiency LE (70.7 Cd/A), lifetime at 80% LT₈₀% (248 hours) and power efficiency PE (40.6 lm/W) of compounds of Formula I, such as Compound 1-O, at a doping concentration of 10% (Example 2) are all higher than the corresponding Comparative Compounds A to E (Comparative Examples 1 to 5) at all three doping concentration 7%, 10% and 13% except the lifetime of Comparative Example 5 LT₈₀% (270 hours). Similarly higher EQE, LE, LT_(80%) and PE of Compound 1-O at a lower doping concentration of 7% (Example 1) can be found when compared with comparative Compound A to E (Comparative Examples 1 to 5). These data clearly demonstrated that compounds of Formula I, such as Compound 1-O is more efficient and longer-lived emitter than comparative compounds A and E.

Combination with Other Materials

The materials described herein as useful for a particular layer in an organic light emitting device may be used in combination with a wide variety of other materials present in the device. For example, emissive dopants disclosed herein may be used in conjunction with a wide variety of hosts, transport layers, blocking layers, injection layers, electrodes and other layers that may be present. The materials described or referred to below are non-limiting examples of materials that may be useful in combination with the compounds disclosed herein, and one of skill in the art can readily consult the literature to identify other materials that may be useful in combination.

HIL/HTL:

A hole injecting/transporting material to be used in the present invention is not particularly limited, and any compound may be used as long as the compound is typically used as a hole injecting/transporting material. Examples of the material include, but not limit to: a phthalocyanine or porphryin derivative; an aromatic amine derivative; an indolocarbazole derivative; a polymer containing fluorohydrocarbon; a polymer with conductivity dopants; a conducting polymer, such as PEDOT/PSS; a self-assembly monomer derived from compounds such as phosphonic acid and sliane derivatives; a metal oxide derivative, such as MoO_(x); a p-type semiconducting organic compound, such as 1,4,5,8,9,12-Hexaazatriphenylenehexacarbonitrile; a metal complex, and a cross-linkable compounds.

Examples of aromatic amine derivatives used in HIL or HTL include, but not limit to the following general structures:

Each of Ar¹ to Ar⁹ is selected from the group consisting aromatic hydrocarbon cyclic compounds such as benzene, biphenyl, triphenyl, triphenylene, naphthalene, anthracene, phenalene, phenanthrene, fluorene, pyrene, chrysene, perylene, azulene; group consisting aromatic heterocyclic compounds such as dibenzothiophene, dibenzofuran, dibenzoselenophene, furan, thiophene, benzofuran, benzothiophene, benzoselenophene, carbazole, indolocarbazole, pyridylindole, pyrrolodipyridine, pyrazole, imidazole, triazole, oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine, indole, benzimidazole, indazole, indoxazine, benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine, pteridine, xanthene, acridine, phenazine, phenothiazine, phenoxazine, benzofuropyridine, furodipyridine, benzothienopyridine, thienodipyridine, benzoselenophenopyridine, and selenophenodipyridine; and group consisting 2 to 10 cyclic structural units which are groups of the same type or different types selected from the aromatic hydrocarbon cyclic group and the aromatic heterocyclic group and are bonded to each other directly or via at least one of oxygen atom, nitrogen atom, sulfur atom, silicon atom, phosphorus atom, boron atom, chain structural unit and the aliphatic cyclic group. Wherein each Ar is further substituted by a substituent selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfonyl, sulfonyl, phosphino, and combinations thereof.

In one aspect, Ar¹ to Ar⁹ is independently selected from the group consisting of

k is an integer from 1 to 20; X¹ to X⁸ is C (including CH) or N; Ar¹ has the same group defined above.

Examples of metal complexes used in HIL or HTL include, but not limit to the following general formula:

M is a metal, having an atomic weight greater than 40; (Y¹—Y²) is a bidentate ligand, Y¹ and Y² are independently selected from C, N, O, P, and S; L is an ancillary ligand; m is an integer value from 1 to the maximum number of ligands that may be attached to the metal; and m+n is the maximum number of ligands that may be attached to the metal.

In one aspect, (Y¹—Y²) is a 2-phenylpyridine derivative.

In another aspect, (Y¹—Y²) is a carbene ligand.

In another aspect, M is selected from Ir, Pt, Os, and Zn.

In a further aspect, the metal complex has a smallest oxidation potential in solution vs. Fc⁺/Fc couple less than about 0.6 V.

Host:

The light emitting layer of the organic EL device of the present invention preferably contains at least a metal complex as light emitting material, and may contain a host material using the metal complex as a dopant material. Examples of the host material are not particularly limited, and any metal complexes or organic compounds may be used as long as the triplet energy of the host is larger than that of the dopant. While the Table below categorizes host materials as preferred for devices that emit various colors, any host material may be used with any dopant so long as the triplet criteria is satisfied.

Examples of metal complexes used as host are preferred to have the following general formula:

M is a metal; (Y³—Y⁴) is a bidentate ligand, Y³ and Y⁴ are independently selected from C, N, O, P, and S; L is an ancillary ligand; m is an integer value from 1 to the maximum number of ligands that may be attached to the metal; and m+n is the maximum number of ligands that may be attached to the metal.

In one aspect, the metal complexes are:

(O—N) is a bidentate ligand, having metal coordinated to atoms O and N.

In another aspect, M is selected from Ir and Pt.

In a further aspect, (Y³—Y⁴) is a carbene ligand.

Examples of organic compounds used as host are selected from the group consisting aromatic hydrocarbon cyclic compounds such as benzene, biphenyl, triphenyl, triphenylene, naphthalene, anthracene, phenalene, phenanthrene, fluorene, pyrene, chrysene, perylene, azulene; group consisting aromatic heterocyclic compounds such as dibenzothiophene, dibenzofuran, dibenzoselenophene, furan, thiophene, benzofuran, benzothiophene, benzoselenophene, carbazole, indolocarbazole, pyridylindole, pyrrolodipyridine, pyrazole, imidazole, triazole, oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine, indole, benzimidazole, indazole, indoxazine, benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine, pteridine, xanthene, acridine, phenazine, phenothiazine, phenoxazine, benzofuropyridine, furodipyridine, benzothienopyridine, thienodipyridine, benzoselenophenopyridine, and selenophenodipyridine; and group consisting 2 to 10 cyclic structural units which are groups of the same type or different types selected from the aromatic hydrocarbon cyclic group and the aromatic heterocyclic group and are bonded to each other directly or via at least one of oxygen atom, nitrogen atom, sulfur atom, silicon atom, phosphorus atom, boron atom, chain structural unit and the aliphatic cyclic group. Wherein each group is further substituted by a substituent selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.

In one aspect, host compound contains at least one of the following groups in the molecule:

R¹ to R⁷ is independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof, when it is aryl or heteroaryl, it has the similar definition as Ar's mentioned above.

k is an integer from 0 to 20.

X¹ to X⁸ is selected from C (including CH) or N.

Z¹ and Z² is selected from NR¹, O, or S.

HBL:

A hole blocking layer (HBL) may be used to reduce the number of holes and/or excitons that leave the emissive layer. The presence of such a blocking layer in a device may result in substantially higher efficiencies as compared to a similar device lacking a blocking layer. Also, a blocking layer may be used to confine emission to a desired region of an OLED.

In one aspect, compound used in HBL contains the same molecule or the same functional groups used as host described above.

In another aspect, compound used in HBL contains at least one of the following groups in the molecule:

k is an integer from 0 to 20; L is an ancillary ligand, m is an integer from 1 to 3.

ETL:

Electron transport layer (ETL) may include a material capable of transporting electrons. Electron transport layer may be intrinsic (undoped), or doped. Doping may be used to enhance conductivity. Examples of the ETL material are not particularly limited, and any metal complexes or organic compounds may be used as long as they are typically used to transport electrons.

In one aspect, compound used in ETL contains at least one of the following groups in the molecule:

R¹ is selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof, when it is aryl or heteroaryl, it has the similar definition as Ar's mentioned above.

Ar¹ to Ar³ has the similar definition as Ar's mentioned above.

k is an integer from 0 to 20.

X¹ to X⁸ is selected from C (including CH) or N.

In another aspect, the metal complexes used in ETL contains, but not limit to the following general formula:

(O—N) or (N—N) is a bidentate ligand, having metal coordinated to atoms O, N or N, N; L is an ancillary ligand; m is an integer value from 1 to the maximum number of ligands that may be attached to the metal.

In any above-mentioned compounds used in each layer of the OLED device, the hydrogen atoms can be partially or fully deuterated.

In addition to and/or in combination with the materials disclosed herein, many hole injection materials, hole transporting materials, host materials, dopant materials, exiton/hole blocking layer materials, electron transporting and electron injecting materials may be used in an OLED. Non-limiting examples of the materials that may be used in an OLED in combination with materials disclosed herein are listed in Table 3 below. Table 3 lists non-limiting classes of materials, non-limiting examples of compounds for each class, and references that disclose the materials.

TABLE 3 MATERIAL EXAMPLES OF MATERIAL PUBLICATIONS Hole injection materials Phthalocyanine and porphryin compounds

Appl. Phys. Lett. 69, 2160 (1996) Starburst triarylamines

J. Lumin. 72-74, 985 (1997) CF_(x) Fluorohydro- carbon polymer

Appl. Phys. Lett. 78, 673 (2001) Conducting polymers (e.g., PEDOT: PSS, polyaniline, polypthio- phene)

Synth. Met. 87, 171 (1997) WO2007002683 Phosphonic acid and sliane SAMs

US20030162053 Triarylamine or polythiophene polymers with conductivity dopants

EP1725079A1

Organic compounds with conductive inorganic compounds, such as molybdenum and tungsten oxides

US20050123751 SID Symposium Digest, 37, 923 (2006) WO2009018009 n-type semiconducting organic complexes

US20020158242 Metal organometallic complexes

US20060240279 Cross-linkable compounds

US20080220265 Polythiophene based polymers and copolymers

WO 2011075644 EP2350216 Hole transporting materials Triarylamines (e.g., TPD, α- NPD)

Appl. Phys. Lett. 51, 913 (1987)

U.S. Pat. No. 5,061,569

EP650955

J. Mater. Chem. 3, 319 (1993)

Appl. Phys. Lett. 90, 183503 (2007)

Appl. Phys. Lett. 90, 183503 (2007) Triaylamine on spirofluorene core

Synth. Met. 91, 209 (1997) Arylamine carbazole compounds

Adv. Mater. 6, 677 (1994), US20080124572 Triarylamine with (di)benzothio- phene/ (di)benzofuran

US20070278938, US20080106190 US20110163302 Indolocarba- zoles

Synth. Met. 111, 421 (2000) Isoindole compounds

Chem. Mater. 15, 3148 (2003) Metal carbene complexes

US20080018221 Phosphorescent OLED host materials Red hosts Arylcarbazoles

Appl. Phys. Lett. 78, 1622 (2001) Metal 8- hydroxy- quinolates (e.g., Alq₃, BAlq)

Nature 395, 151 (1998)

US20060202194

WO2005014551

WO2006072002 Metal phenoxybenzo- thiazole compounds

Appl. Phys. Lett. 90, 123509 (2007) Conjugated oligomers and polymers (e.g., polyfluorene)

Org. Electron. 1, 15 (2000) Aromatic fused rings

WO2009066779, WO2009066778, WO2009063833, US20090045731, US20090045730, WO2009008311, US20090008605, US20090009065 Zinc complexes

WO2010056066 Chrysene based compounds

WO2011086863 Green hosts Arylcarbazoles

Appl. Phys. Lett. 78, 1622 (2001)

US20030175553

WO2001039234 Aryltriphenyl- ene compounds

US20060280965

US20060280965

WO2009021126 Poly-fused heteroaryl compounds

US20090309488 US20090302743 US20100012931 Donor acceptor type molecules

WO2008056746

WO2010107244 Aza- carbazole/ DBT/DBF

JP2008074939

US20100187984 Polymers (e.g., PVK)

Appl. Phys. Lett. 77, 2280 (2000) Spirofluorene compounds

WO2004093207 Metal phenoxybenzo- oxazole compounds

WO2005089025

WO2006132173

JP200511610 Spirofluorene- carbazole compounds

JP2007254297

JP2007254297 Indolo- cabazoles

WO2007063796

WO2007063754 5-member ring electron deficient heterocycles (e.g., triazole, oxadiazole)

J. Appl. Phys. 90, 5048 (2001)

WO2004107822 Tetraphenylene complexes

US20050112407 Metal phenoxy- pyridine compounds

WO2005030900 Metal coordination complexes (e.g., Zn, Al with N{circumflex over ( )}N ligands)

US20040137268, US20040137267 Blue hosts Arylcarbazoles

Appl. Phys. Lett. 82, 2422 (2003)

US20070190359 Dibenzothio- phene/Dibenzo- furan-carbazole compounds

WO2006114966, US20090167162

US20090167162

WO2009086028

US20090030202, US20090017330

US20100084966 Silicon aryl compounds

US20050238919

WO2009003898 Silicon/ Germanium aryl compounds

EP2034538A Aryl benzoyl ester

WO2006100298 Carbazole linked by non- conjugated groups

US20040115476 Aza-carbazoles

US20060121308 High triplet metal organometallic complex

U.S. Pat. No. 7,154,114 Phosphorescent dopants Red dopants Heavy metal porphyrins (e.g., PtOEP)

Nature 395, 151 (1998) Iridium(III) organometallic complexes

Appl. Phys. Lett. 78, 1622 (2001)

US2006835469

US2006835469

US20060202194

US20060202194

US20070087321

US20080261076 US20100090591

US20070087321

Adv. Mater. 19, 739 (2007)

WO2009100991

WO2008101842

U.S. Pat. No. 7,232,618 Platinum(II) organometallic complexes

WO2003040257

US20070103060 Osminum(III) complexes

Chem. Mater. 17, 3532 (2005) Ruthenium(II) complexes

Adv. Mater. 17, 1059 (2005) Rhenium (I), (II), and (III) complexes

US20050244673 Green dopants Iridium(III) organometallic complexes

Inorg. Chem. 40, 1704 (2001)

US20020034656

U.S. Pat. No. 7,332,232

US20090108737

WO2010028151

EP1841834B

US20060127696

US20090039776

U.S. Pat. No. 6,921,915

US20100244004

U.S. Pat. No. 6,687,266

Chem. Mater. 16, 2480 (2004)

US20070190359

US 20060008670 JP2007123392

WO2010086089, WO2011044988

Adv. Mater. 16, 2003 (2004)

Angew. Chem. Int. Ed. 2006, 45, 7800

WO2009050290

US20090165846

US20080015355

US20010015432

US20100295032 Monomer for polymeric metal organometallic compounds

U.S. Pat. No. 7,250,226, U.S. Pat. No. 7,396,598 Pt(II) organometallic complexes, including polydentated ligands

Appl. Phys. Lett. 86, 153505 (2005)

Appl. Phys. Lett. 86, 153505 (2005)

Chem. Lett. 34, 592 (2005)

WO2002015645

US20060263635

US20060182992 US20070103060 Cu complexes

WO2009000673

US20070111026 Gold complexes

Chem. Commun. 2906 (2005) Rhenium(III) complexes

Inorg. Chem. 42, 1248 (2003) Osmium(II) complexes

U.S. Pat. No. 7,279,704 Deuterated organometallic complexes

US20030138657 Organometallic complexes with two or more metal centers

US20030152802

U.S. Pat. No. 7,090,928 Blue dopants Iridium(III) organometallic complexes

WO2002002714

WO2006009024

US20060251923 US20110057559 US20110204333

U.S. Pat. No. 7,393,599, WO2006056418, US20050260441, WO2005019373

U.S. Pat. No. 7,534,505

WO2011051404

U.S. Pat. No. 7,445,855

US20070190359, US20080297033 US20100148663

U.S. Pat. No. 7,338.722

US20020134984

Angew. Chem. Int. Ed. 47, 1 (2008)

Chem. Mater. 18, 5119 (2006)

Inorg. Chem. 46, 4308 (2007)

WO2005123873

WO2005123873

WO2007004380

WO2006082742 Osmium(II) complexes

U.S. Pat. No. 7,279,704

Organometallics 23, 3745 (2004) Gold complexes

Appl. Phys. Lett. 74, 1361 (1999) Platinum(II) complexes

WO2006098120, WO2006103874 Pt tetradentate complexes with at least one metal-carbene bond

U.S. Pat. No. 7,655,323 Exciton/hole blocking layer materials Bathocuprine compounds (e.g., BCP, BPhen)

Appl. Phys. Lett. 75, 4 (1999)

Appl. Phys. Lett. 79, 449 (2001) Metal 8- hydroxy- quinolates (e.g., BAlq)

Appl. Phys. Lett. 81, 162 (2002) 5-member ring electron deficient heterocycles such as triazole, oxadiazole, imidazole, benzoimidazole

Appl. Phys. Lett. 81, 162 (2002) Triphenylene compounds

US20050025993 Fluorinated aromatic compounds

Appl. Phys. Lett. 79, 156 (2001) Phenothiazine- S-oxide

WO2008132085 Silylated five- membered nitrogen, oxygen, sulfur or phosphorus dibenzohetero- cycles

WO2010079051 Aza-carbazoles

US20060121308 Electron trnasporting materials Anthracene- benzoimidazole compounds

WO2003060956

US20090179554 Aza triphenylene derivatives

US2009115316 Anthracene- benzothiazole compounds

Appl. Phys. Lett. 89, 063504 (2006) Metal 8- hydroxy- quinolates (e.g., Alq₃, Zrq₄)

Appl. Phys. Lett. 51, 913 (1987) U.S. Pat. No. 7,230,107 Metal hydroxy- benoquinolates

Chem. Lett. 5, 905 (1993) Bathocuprine compounds such as BCP, BPhen, etc

Appl. Phys. Lett. 91, 263503 (2007)

Appl. Phys. Lett. 79, 449 (2001) 5-member ring electron deficient heterocycles (e.g., triazole, oxadiazole, imidazole, benzoimida- zole)

Appl. Phys. Lett. 74, 865 (1999)

Appl. Phys. Lett. 55, 1489 (1989)

Jpn. J. Apply. Phys. 32, L917 (1993) Silole compounds

Org. Electron. 4, 113 (2003) Arylborane compounds

J. Am. Chem. Soc. 120, 9714 (1998) Fluorinated aromatic compounds

J. Am. Chem. Soc. 122, 1832 (2000) Fullerene (e.g., C60)

US20090101870 Triazine complexes

US20040036077 Zn (N{circumflex over ( )}N) complexes

U.S. Pat. No. 6,528,187

EXPERIMENTAL

Chemical abbreviations used throughout this document are as follows: Cy is cyclohexyl, dba is dibenzylideneacetone, EtOAc is ethyl acetate, DME is dimethoxyethane, dppe is 1,2-bis(diphenylphosphino)ethane, dppf is 1,1′-Bis(diphenylphosphino)ferrocene, THF is tetrahydrofuran, DCM is dichloromethane, S-Phos is dicyclohexyl(2′,6′-dimethoxy-[1,1′-biphenyl]-2-yl)phosphine.

Synthesis of Compound 1-O

Synthesis of 2,6-diisopropyl-N-(2-nitrophenyl)aniline: 1-Bromo-2-nitrobenzene (15 g, 75 mmol), 2,6-diisopropylaniline (14.0 mL, 75 mmol) and cesium carbonate (41.5 g, 127 mmol) were mixed in 500 mL of toluene and the solution was bubbled with nitrogen for 20 minutes. Pd₂(dba)₃ (1.36 g, 1.49 mmol) and dicyclohexyl(2′,6′-dimethoxy-[1,1′-biphenyl]-2-yl)phosphine (2.44 g, 5.94 mmol) were added and reaction mixture was heated to reflux for 18 hours. After cooling, the organic layer separated and the aqueous layer was extracted with 3×50 mL dichloromethane and dried over sodium sulfate. After removing the solvent under reduced pressure, the crude product was chromatographed on silica gel with 10:90 ethyl acetate:hexane (v/v) and 20 g (72%) of the product was obtained. The product was confirmed by GC/MS, NMR and HPLC (99.96% pure)

Synthesis of N-(2,6-diisopropylphenyl)benzene-1,2-diamine: Diisopropyl-N-(2-nitrophenyl) aniline (12 g, 40.2 mmol) was dissolved in 200 mL ethanol and palladium on carbon (0.642 g) was added. The reaction mixture was placed on the Parr hydrogenator for 1 hour. The reaction mixture was filtered through a Celite® (diatomaceous earth) plug, washed with dichloromethane and evaporated. The crude product was chromatographed on silica gel with 10:90 ethyl acetate:hexane (v/v) and 10 g (93%) of the product was obtained. The product was confirmed by GC/MS and NMR.

Synthesis of benzo[b,d]furan-4-carbaldehyde: A 1 L round bottom flask was charged with 2,4-dibenzo[b,d]furan (24 g, 143 mmol) in 300 mL THF, cooled to −78° C. Butyl lithium (98 mL, 157 mmol) was added very slowly. The reaction was warmed up to room temperature for five hours. The reaction was cooled back to −78° C. N,N-dimethylformamide (14.36 mL, 186 mmol) was dissolved in 50 mL THF and added very slowly over the reaction. The reaction was warmed up to room temperature overnight. 300 mL of brine was added to the reaction. After separation of the layers, the aqueous layer was extracted with ethyl acetate (2×100 mL). After removal of the solvent, the crude product was subjected to column chromatography (SiO₂, 10% ethyl acetate and 10% DCM in hexane), then crystallized from hexane to get 14 g (50.2%) purified product.

Synthesis of 2-(dibenzo[b,d]furan-4-yl)-1-(2,6-diisopropylphenyl)-1-H-benzo[d]imidazole: N-(2,6-diisopropylphenyl)benzene-1,2-diamine (4.5 g, 16.77 mmol), dibenzo[b,d]furan-4-carbldehyde (4.93 g, 25.1 mmol) and 1-hexadecylpyridinium bromide (0.322 g, 0.838 mmol) were dissolved in 10 mL THF and 200 mL water and stirred at room temperature overnight. GC/MS analysis of the reaction mixture typically showed the presence of a mixture of the phenylbenzimidazole product and the phenyl-2,3-dihydro-1H-benzo[d]imidazole product (ca. 50:50). Brine (200 mL) was added and the reaction mixture which was extracted with EtOAc (3×300 mL), dried over sodium sulfate and evaporated. The total crude yield was 7 g (94%) and the product was carried onto the next step without further purification.

Synthesis of 2-(dibenzo[b,d]furan-4-yl)-1-(2,6-diisopropylphenyl)-1-H-benzo[d]imidazole: The mixture of the dibenzofuranbenzimidazole product and the dibenzofuran-2,3-dihydro-1H-benzo[d]imidazole product (7 g, 15.67 mmol) from the previous step was combined and manganese(IV) oxide (13.6 g, 156 mmol) in 100 mL of toluene. With vigorous stirring, the reaction was heated to reflux for 16 hours, cooled, filtered through a plug of silica gel eluted with dichloromethane and evaporated. The crude product was chromatographed on silica gel with 0-3% ethyl acetate in dichloromethane and then recrystallized from hexane to give 4.3 g (61.7%) of the product. The product was confirmed by HPLC and NMR.

Synthesis of Compound 1-O: A mixture of iridium trifluormethanesulfonate complex (2.0 g, 2.75 mmol 2-(dibenzo[b,d]furan-4-yl)-1-(2,6-diisopropylphenyl)-1H-benzo[d]imidazole (3.67 g, 8.24 mmol) in EtOH (25 mL) and MeOH (25 mL) was refluxed for 20 hours under nitrogen atmosphere. The reaction mixture was cooled back to room temperature, diluted with ethanol and Celite® (diatomaceous earth) was added and the mixture stirred for 10 minutes. The mixture was filtered on a small silica get plug and washed with ethanol (3-4 times) and with hexane (3-4 times). The filtrate was discarded. The Celite® (diatomaceous earth)silica plug was then washed with dichloromethane to elute the product. The crude product was chromatographed on silica gel with 30% DCM/hexane. The product was chromatographed again on silica gel eluting with 20-30% THF in hexane. 0.32 g (12.5%) of Compound 1-O was obtained after sublimation, which was confirmed by LC-MS.

Synthesis of Compound 12O.

Synthesis of 4-iodobenzo[b,d]furan: A 1 L round bottom flask was charged with 2,4-dibenzo[b,d]furan (25 g, 149 mmol) in 300 mL of THF and cooled to −78° C. n-Butyl lithium (102 mL, 164 mmol) was added slowly. The reaction was warmed up to room temperature for five hours. The reaction was cooled back to −78° C. Iodine (37.7 g, 149 mmol) was dissolved in 50 mL of THF and added slowly to the reaction. The reaction was warmed up to room temperature overnight. 300 mL of aqueous sodium bicarbonate was added to the reaction. After separation of the layers, the aqueous layer was extracted with ethyl acetate (2×100 mL). After removal of the solvent, the crude product was subjected to column chromatography (SiO₂, 3% ethyl acetate in hexane), then crystallized from hexane to get 30 g pure product (70%).

Synthesis of dibenzo-[b,d]furan-4-carbonitrile: 4-Iododibenzo-[b,d]furan (11.5 g, 39.1 mmol) 1,1′-Bis(diphenylphosphino)ferrocene (dppf) (0.867 g, 1.564 mmol), dicyanozinc (2.75 g, 23.46 mmol), 10% Pd/C (0.416 g, 0.391 mmol) and 100 mL of dimethylacetamide (DMAC) were placed in 3 neck flask. Nitrogen was bubbled for 10 minutes. Bis-(formyloxy) zinc (0.608 g, 3.91 mmol) was added to the reaction and degassed with nitrogen again for 10 minutes, then heated to 105° C. under nitrogen for 3 hours. The reaction was cooled down to room temperature diluted with 100 mL ethyl acetate. This reaction mixture was filtered and washed with ethyl acetate. The organic layer washed with 2×100 mL water and 1×100 mL 5% NH₄OH. The crude product was subject to chromatography, eluting with 5% ethyl acetate in hexane to obtain 5.2 g (68.8%) of purified product.

Synthesis of 1-(2,6-diisopropylphenyl)dibenzo[b,d]-3-yl)furan-4-carboximidamide: Trimethylaluminum (10.35 mL, 20.7 mmol) was added slowly into 2,6-diisopropylaniline (3.90 mL, 20.70 mmol) in 100 mL toluene at 0° C. under nitrogen. The reaction was allowed to stir at room temperature for 2 hours. N-(2,6-diisopropylphenyl)dibenzo[b,d]furan-4-carboximidamide in 50 mL toluene was added to the reaction and heated to 70° C. overnight. The reaction was cooled down with ice bath and poured into a stirring slurry silica gel in 2:1 DCM/methanol (v/v) and filtered and washed with DCM and methanol. After solvent evaporation, the solid was triturated with hexane to give 5.5 g (71.7%) of product.

Synthesis of 2-(dibenzo[b,d]-3-yl)furan-4-yl)-1-(2,6-diisopropylphenyl)-1H-imidazole: N-(2,6-diisopropylphenyl)dibenzo[b,d]furan-4-carboximidamide (7 g, 18.89 mmol), chloroacetaldehyde (4.80 mL, 37.8 mmol) and sodium bicarbonate (3.17 g, 37.8 mmol) in 100 mL of 2-propanol was heated up to reflux for 3 hours under nitrogen. The reaction was cooled to room temperature and diluted with 100 mL water and 100 mL ethyl acetate. The mixture was separated on an alumina (Al₂O₃) column, eluting with DCM/methanol 0-10%, to obtain 3.05 g (51.2%) of pure product.

Synthesis of Compound 12-O: A mixture of iridium trifluormethanesulfonate complex (1.6 g, 2.04 mmol) and 2-(dibenzo[b,d]furan-4-yl)-1-(2,6-diisopropylphenyl)-1H-imidazole (2.013 g, 5.10 mmol) in EtOH (25 mL) and MeOH (25 mL) was refluxed for 20 hours under nitrogen atmosphere. The reaction mixture was cooled to room temperature and diluted with ethanol. Celite® (diatomaceous earth) was added to the mixture with stirring for 10 minutes. The mixture was filtered on a small silica gel plug and washed with ethanol (3-4 times) and hexane (3-4 times). The Celite® (diatomaceous earth)/silica plug was then washed with dichloromethane until no more material came through. The DCM filtrate was evaporated and run a reverse silica column to obtain 0.85 g (43.8%) of product, which was confirmed by LC-MS.

It is understood that the various embodiments described herein are by way of example only, and are not intended to limit the scope of the invention. For example, many of the materials and structures described herein may be substituted with other materials and structures without deviating from the spirit of the invention. The present invention as claimed may therefore include variations from the particular examples and preferred embodiments described herein, as will be apparent to one of skill in the art. It is understood that various theories as to why the invention works are not intended to be limiting. 

The invention claimed is:
 1. A compound having a structure of formula:

wherein R₁, R₂, and R₃ represent mono-, di-, tri-, tetra-substitution or no substitution; wherein R₁, R₂, and R₃ are independently selected from the group consisting of hydrogen, deuterium, alkyl, cycloalkyl, heteroalkyl, and combinations thereof; wherein R4 is

wherein ring C is a 6-membered carbocyclic ring; wherein R′₁, R′₂, and R′₃ are selected from the group consisting of hydrogen, deuterium, alkyl, aryl, and combination thereof; wherein at least one of R′₁ and R′₂ is not hydrogen or deuterium; wherein R₇ represents mono-, di-, tri-, or tetra-substitution; wherein R₇ is selected from the group consisting of hydrogen and a substitution selected from the group consisting of halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, combinations thereof, and partially or fully deuterated variations thereof; wherein X is selected from the group consisting of O, S, and Se; wherein m is 1 or 2; and wherein at least one of the following is true: (i) at least one R₇ is a substitution; and (ii)(b) at least two R₂ are independently selected from the group consisting of alkyl, cycloalkyl, heteroalkyl, combinations thereof, and partially or fully deuterated variations thereof.
 2. The compound of claim 1, wherein: (ii)(b) at least two R₂ are independently selected from the group consisting of alkyl, cycloalkyl, heteroalkyl, combinations thereof, and partially or fully deuterated variations thereof.
 3. The compound of claim 1, wherein (i) at least one R₇ is selected from the group consisting of alkyl, cycloalkyl, heteroalkyl, arylalkyl, aryl, heteroaryl, combinations thereof, and partially or fully deuterated variations thereof.
 4. The compound of claim 1, wherein ring C is phenyl.
 5. The compound of claim 1, wherein R′₁ and R′₂ are selected from the group consisting of methyl, ethyl, isopropyl, and phenyl; and wherein R′₃ is H.
 6. The compound of claim 1, wherein R′₁ is isopropyl, R′₂ is isopropyl, and R′₃ is H.
 7. The compound of claim 1, wherein X is O.
 8. The compound of claim 1, wherein the compound is


9. The compound of claim 1, wherein the compound is


10. The compound of claim 1, wherein m is
 2. 11. A first device comprising a first organic light emitting device, comprising: an anode; a cathode; and an organic layer, disposed between the anode and the cathode, comprising a compound having a structure of formula:

wherein R₁, R₂, and R₃ represent mono-, di-, tri-, tetra-substitution or no substitution; wherein R₁, R₂, and R₃ are independently selected from the group consisting of hydrogen, deuterium, alkyl, cycloalkyl, heteroalkyl, and combinations thereof; wherein R4 is

wherein ring C is a 6-membered carbocyclic ring; wherein R′₁, R′₂, and R′₃ are selected from the group consisting of hydrogen, deuterium, alkyl, aryl, and combination thereof; wherein at least one of R′₁ and R′₂ is not hydrogen or deuterium; wherein R₇ represents mono-, di-, tri-, or tetra-substitution; wherein R₇ is selected from the group consisting of hydrogen and a substitution selected from the group consisting of halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, combinations thereof, and partially or fully deuterated variations thereof; wherein X is selected from the group consisting of O, S, and Se; wherein m is 1 or 2; and wherein at least one of the following is true: (i) at least one R₇ is a substitution; and (ii)(b) at least two R₂ are independently selected from the group consisting of alkyl, cycloalkyl, heteroalkyl, combinations thereof, and partially or fully deuterated variations thereof.
 12. The device of claim 11, wherein: (ii)(b) at least two R₂ are independently selected from the group consisting of alkyl, cycloalkyl, heteroalkyl, combinations thereof, and partially or fully deuterated variations thereof.
 13. The first device of claim 11, wherein the first device is selected from the group consisting of a consumer product, an organic light emitting device, and a lighting panel.
 14. The first device of claim 11, wherein the organic layer is an emissive layer and the compound is an emissive dopant.
 15. The first device of claim 11, wherein the organic layer is an emissive layer and the compound is a non-emissive dopant.
 16. The first device of claim 11, wherein the organic layer further comprises a host.
 17. The first device of claim 16, wherein the host comprises a triphenylene containing benzo-fused thiophene or benzo-fused furan; wherein any substituent in the host is an unfused substituent independently selected from the group consisting of C_(n)H_(2n+1), OC_(n)H_(2n+1), OAr₁, N(C_(n)H_(2n+1))₂, N(Ar₁)(Ar₂), CH═CH—C_(n)H_(2n+1), C≡CC_(n)H_(2n+1), Ar₁, Ar₁—Ar₂, and C_(n)H_(2n)—Ar₁; wherein n is from 1 to 10; and wherein Ar₁ and Ar₂ are independently selected from the group consisting of benzene, biphenyl, naphthalene, triphenylene, carbazole, and heteroaromatic analogs thereof.
 18. The first device of claim 17, wherein the host comprises one or more compounds having the formula:

wherein p is 0 or
 1. 19. The first device of claim 16, wherein the host is selected from the group consisting of:

and combinations thereof.
 20. The first device of claim 16, wherein the host comprises a metal complex.
 21. The device of claim 11, wherein X is O.
 22. The device of claim 11, wherein the compound is


23. The device of claim 11, wherein the compound is


24. The device of claim 11, wherein at least one R7 is selected from the group consisting of alkyl, cycloalkyl, heteroalkyl, arylalkyl, aryl, heteroaryl, combinations thereof, and partially or fully deuterated variations thereof. 